Small Circuit for Blinking LEDs?

[Tchail]

I know that you can buy flashing LEDs.

And I've also built a couple of kits that allow you to create flashing LEDs.

But does anyone know what is the smallest circuit out there that can flash a 3v surface-mount LED?

I ask this because I got my hands on several "body lights" from Thatscoolwire.com.

http://www.thatscoolwire.com/store/subc ... goryID=165

These include several surface-mount LEDs that apparently flash in a random pattern.

Any advice would be greatly appreciated.

-Tchail

[tetsujin]

Probably the smallest circuit you can get to flash an LED is a "blinking LED". Blinking LEDs have the flasher circuit built-in. A blinking LED doesn't pass current when it's "off", so you should be able to wire a second LED in series and make them both blink (if the first blinking LED doesn't produce the color you want or something...)

A blinker circuit can be very simple - but to make it yourself, and make it small, may be more work than it's worth. You could use something like an "Arduino Pro Mini" (18mm x 33mm) or "Teensy" (18mm x 31mm) - program it to blink one LED or a dozen however you want... A microcontroller is definitely overkill for a job like blinking a LED, but in a way it's sometimes not worth going with anything less. And microcontroller solutions can be very small, since you don't really need more than the IC and a board to put it on. I have a microcontroller board that I designed for myself that's around 1cm square (the smallest is around 9mm x 10mm) - I can fit one of those almost anywhere.

[opal_1970]

If you are going to use an Arduino, you can export your code to an ATtiny85 microcontroller for example, and then just hook up your power/GND and LEDs to one or all of its 5 Output pins and you are good to go, and you do not need to put the much larger arduino in your build. Each output can support a separate blink pattern, the number of LEDs that you can hook up to each pin is dependent on how much power you are running. The ATtiny85 is about the size of your fingertip, perhaps somewhat smaller. There are other chips that are bigger if you need more than 5 outputs, but the 85 is the smallest that I am aware of.

check out this site for an excellent how-to...

http://blog.makezine.com/2011/10/10/how ... -projects/